The present invention generally relates to transmission of a reference laser beam and, in particular, to an apparatus and method for dithering or oscillating a reference laser beam about one or more target areas.
Laser systems have been employed in numerous surveying and construction applications. In one such system, a laser light transmitting device provides a rotating laser beam that establishes a reference plane. Typically, the rotating laser beam is used to define, in effect, a continuous plane of light as a constant horizontal bench mark of elevation over an entire work area. The laser light is either detected by the naked eye or by one or more laser beam detectors placed at considerable distances from the transmitting device.
In a laser light transmitting device, a generally horizontal plane of light is produced by projecting the beam upward and then deflecting the beam ninety degrees within a pentaprism or penta-mirror assembly. The pentaprism assembly is rotated about a generally vertical axis within the transmitting device to cause the horizontal beam to sweep around the axis and define the horizontal plane.
Conventional laser transmitters incorporate a dither mode wherein a reference laser beam is dithered across a defined zone. The dither zone boundaries are set by physically moving a reflective target to locations corresponding to the preferred dither zone boundaries. Thus, typically, the user is forced to move the target from one end of the dither zone to the opposite end to define the zone. This may be difficult if the user is in a hazardous environment, on a ladder, etc. Further, care must be taken not to lose the laser beam as the user moves the target.
Accordingly, there is a need for a reference laser beam transmitter incorporating a target dither mode wherein the dither zone may be defined conveniently, without requiring a user to move the target along the entire extent of the dither zone.